An appropriateness index for improvements in Emergency Medical Services will be developed through a series of three closely linked analyses. Improvements are "appropriate" only given the characteristics of a desired system and knowledge of the desired components of EMS are available in the study area. Changes in an EMS system in one place frequently affect service in adjoining places, so the second analysis will develop a mathematical model to account for the spatial availability of EMS components. The third analysis will use location-allocation algorithms to compare the appropriateness of alternative improvement plans. By comparing the extent of improvement the would be produced by implemenation of a plan with the improvement possible from an optimal plan an appropriateness score will be generated. The objective function of the optimal plan or plans will be defined by EMS planners and administrators at different levels in the national EMS network. The methodology will be replicable in any location. Results of the research will make it possible to make more rational investment decisions regarding EMS components such that the right improvement for the right place can be identified.